Contract Health Service Delivery Area Counties Research Articles

Racial misclassification of American Indians and Alaska Natives by Indian Health Service Contract Health Service Delivery Area.

We evaluated the racial misclassification of American Indians and Alaska Natives (AI/ANs) in cancer incidence and all-cause mortality data by Indian Health Service (IHS) Contract Health Service Delivery Area (CHSDA). We evaluated data from 3 sources: IHS-National Vital Statistics System (NVSS), IHS-National Program of Cancer Registries (NPCR)/Surveillance, Epidemiology and End Results (SEER) program, and National Longitudinal Mortality Study (NLMS). We calculated, within each data source, the sensitivity and classification ratios by sex, IHS region, and urban-rural classification by CHSDA county. Sensitivity was significantly greater in CHSDA counties (IHS-NVSS: 83.6%; IHS-NPCR/SEER: 77.6%; NLMS: 68.8%) than non-CHSDA counties (IHS-NVSS: 54.8%; IHS-NPCR/SEER: 39.0%; NLMS: 28.3%). Classification ratios indicated less misclassification in CHSDA counties (IHS-NVSS: 1.20%; IHS-NPCR/SEER: 1.29%; NLMS: 1.18%) than non-CHSDA counties (IHS-NVSS: 1.82%; IHS-NPCR/SEER: 2.56%; NLMS: 1.81%). Race misclassification was less in rural counties and in regions with the greatest concentrations of AI/AN persons (Alaska, Southwest, and Northern Plains). Limiting presentation and analysis to CHSDA counties helped mitigate the effects of race misclassification of AI/AN persons, although a portion of the population was excluded.

Period life tables for the non-Hispanic American Indian and Alaska Native population, 2007-2009.

We estimated complete period life tables for the non-Hispanic American Indian and Alaska Native (AI/AN) population residing in Contract Health Service Delivery Area (CHSDA) counties for the period 2007-2009. We used National Vital Statistics System mortality data files for years 2007-2009 corrected for AI/AN misclassification on death certificates, midyear 2008 revised census bridged race intercensal population estimates, and National Vital Statistics System birth data for years 2006-2009. We used the same methodology as that used to estimate official US annual life tables, with some minor modifications. For the period 2007-2009, the non-Hispanic AI/AN population in CHSDA counties had the lowest life expectancy at birth (71.1 years) of any racial/ethnic group for which official US life tables are estimated. By comparison, in 2008, life expectancy at birth was 73.9 years for the non-Hispanic Black population, 78.4 years for the non-Hispanic White population, and 80.8 years for the Hispanic population. The life tables showed a clear mortality disadvantage for the non-Hispanic AI/AN population in CHSDA counties relative to other national populations. The findings suggested that further research is necessary to explore the causes behind these disadvantages.

Methods for improving the quality and completeness of mortality data for American Indians and Alaska Natives.

We describe methods used to mitigate the effect of race misclassification in mortality records and the data sets used to improve mortality estimates for American Indians and Alaska Natives (AI/ANs). We linked US National Death Index (NDI) records with Indian Health Service (IHS) registration records to identify AI/AN deaths misclassified as non-AI/AN deaths. Analyses excluded decedents of Hispanic origin and focused on Contract Health Service Delivery Area (CHSDA) counties. We compared death rates for AI/AN persons and Whites across 6 US regions. IHS registration records merged to 176,137 NDI records. Misclassification of AI/AN race in mortality data ranged from 6.3% in the Southwest to 35.6% in the Southern Plains. From 1999 to 2009, the all-cause death rate in CHSDA counties for AI/AN persons varied by geographic region and was 46% greater than that for Whites. Analyses for CHSDA counties resulted in higher death rates for AI/AN persons than in all counties combined. Improving race classification among AI/AN decedents strengthens AI/AN mortality data, and analyzing deaths by geographic region can aid in planning, implementation, and evaluation of efforts to reduce health disparities in this population.

Lung Cancer Deaths Among American Indians and Alaska Natives, 1990–2009

We examined regional differences in lung cancer among American Indians/Alaska Natives (AI/ANs) using linked data sets to minimize racial misclassification. On the basis of federal lung cancer incidence data for 1999 to 2009 and deaths for 1990 to 2009 linked with Indian Health Service (IHS) registration records, we calculated age-adjusted incidence and death rates for non-Hispanic AI/AN and White persons by IHS region, focusing on Contract Health Service Delivery Area (CHSDA) counties. We correlated death rates with cigarette smoking prevalence and calculated mortality-to-incidence ratios. Lung cancer death rates among AI/AN persons in CHSDA counties varied across IHS regions, from 94.0 per 100,000 in the Northern Plains to 15.2 in the Southwest, reflecting the strong correlation between smoking and lung cancer. For every 100 lung cancers diagnosed, there were 6 more deaths among AI/AN persons than among White persons. Lung cancer death rates began to decline in 1997 among AI/AN men and are still increasing among AI/AN women. Comparison of regional lung cancer death rates between AI/AN and White populations indicates disparities in tobacco control and prevention interventions. Efforts should be made to ensure that AI/AN persons receive equal benefit from current and emerging lung cancer prevention and control interventions.

Cancer among American Indians and Alaska Natives in the United States, 1999-2004

Cancer incidence rates vary among American Indian and Alaska Native (AI/AN) populations and often differ from rates among non-Hispanic whites (NHWs). However, the misclassification of race for AI/AN cancer cases in central cancer registries may have led to underestimates of the AI/AN cancer burden in previous reports. Cases diagnosed during 1999 through 2004 were identified from population-based cancer registries in the United States. Age-adjusted rates were calculated for the 25 most common sites for AI/ANs and NHWs. To minimize the misclassification of race, cancer registry records were linked with patient registration files from the Indian Health Service (IHS). Analyses were restricted to Contract Health Service Delivery Area (CHSDA) counties and were stratified by IHS region. In CHSDA counties, cancer incidence rates among AI/ANs varied widely by region, whereas rates among NHWs did not. For all cancer sites combined, AI/AN rates were higher than NHW rates among both males and females in the Northern and Southern Plains, and among Alaska Native Females; AI/AN rates were lower than NHW rates in the Southwest, the Pacific Coast, and the East. Lung cancer and colorectal cancer rates for AI/ANs exceeded rates for NHWs in Alaska and the Northern Plains. Rates for stomach, gallbladder, kidney, and liver cancer were higher among AI/ANs than among NHWs overall, in Alaska, in the Plains regions, and in the Southwest. Regional differences in cancer incidence rates among AI/AN populations were not obvious from nationwide data and highlighted opportunities for cancer control and prevention. It is unlikely that such differences are explained by race misclassification.

Gallbladder cancer incidence among American Indians and Alaska Natives, US, 1999-2004

Gallbladder cancer (GBC) is rare; however, it disproportionately affects the American Indian and Alaska Natives (AI/AN) population. The purpose of the study was to characterize GBC among AI/AN in the US population. Cases of GBC diagnosed between 1999 and 2004 and collected by state-based cancer registries were included. Registry records were linked with Indian Health Service (IHS) administration records to decrease race misclassification of AI/AN. GBC rates and/or percent distributions for AI/AN and non-Hispanic whites (NHW) were calculated by sex, IHS region, age, and stage for all US counties and IHS Contract Health Service Delivery Area (CHSDA) counties, in which approximately 56% of US AI/AN individuals reside. In CHSDA counties, the GBC incidence rate among AI/AN was 3.3 per 100,000, which was significantly higher than that among NHW (P < .05). Rates varied widely among IHS regions and ranged from 1.5 in the East to 5.5 in Alaska. Rates were higher among AI/AN females than males in all regions, except the Northern Plains. Higher percentages of GBC were diagnosed among AI/AN aged <65 years compared with NHW. GBC was most often diagnosed at the regional stage among AI/AN, whereas GBC was most often diagnosed at regional or distant stages among NHW. To the authors' knowledge to date, this is the most comprehensive study of GBC incidence among AI/AN in the US. The accurate characterization of GBC in this population could help inform the development of interventions aimed at reducing morbidity and mortality from this disease.

Methods for improving cancer surveillance data in American Indian and Alaska Native populations

The misclassification of race decreases the accuracy of cancer incidence data for American Indians and Alaska Natives (AI/ANs) in some central cancer registries. This article describes the data sources and methods that were used to address this misclassification and to produce the cancer statistics used by most of the articles in this supplement. Records from United States cancer registries were linked with Indian Health Service (IHS) records to identify AI/AN cases that were misclassified as non-AI/AN. Data were available from 47 registries that linked their data with IHS, met quality criteria, and agreed to participate. Analyses focused on cases among AI/AN residents in IHS Contract Health Service Delivery Area (CHSDA) counties in 33 states. Cancer incidence and stage data were compiled for non-Hispanic whites (NHWs) and AI/ANs across 6 IHS regions of the United States for 1999 through 2004. Misclassification of AI/AN race as nonnative in central cancer registries ranged from 85 individuals in Alaska (3.4%) to 5297 individuals in the Southern Plains (44.5%). Cancer incidence rates among AI/ANs for all cancers combined were lower than for NHWs, but incidence rates varied by geographic region for AI/ANs. Restricting the rate calculations to CHSDA counties generally resulted in higher rates than those obtained for all counties combined. The classification of race for AI/AN cases in cancer registries can be improved by linking records to the IHS and stratifying by CHSDA counties. Cancer in the AI/AN population is clarified further by describing incidence rates by geographic region. Improved cancer surveillance data for AI/AN communities should aid in the planning, implementation, and evaluation of more effective cancer control and should reduce health disparities in this population.

Lung cancer incidence among American Indians and Alaska Natives in the United States, 1999-2004.

Lung cancer incidence rates among American Indians and Alaska Natives (AI/ANs) in the United States have not been described well, primarily because of race misclassification and, until the 1990s, incomplete coverage of their population by cancer registries. Smoking, the predominant cause of lung cancer, is particularly prevalent among this population. Data from the National Program of Cancer Registries and the Surveillance, Epidemiology, and End Results Program were combined to estimate age-adjusted incidence rates of lung cancer during 1999 through 2004. Cases were linked to Indian Health Service (IHS) registration databases to identify AI/ANs whose race may have been misclassified. Age-adjusted rates were calculated for Contract Health Service Delivery Area (CHSDA) counties and for all counties by IHS region, and comparisons were made between AI/ANs and non-Hispanic whites (NHWs). Among populations living in CHSDA counties, NHWs overall had higher rates of lung cancer than AI/ANs. However, the rates (per 100,000 population) among AI/ANs varied substantially between IHS regions from 14.9 (Southwest) to 87.1 (Southern Plains), 93.2 (Alaska), and 104.3 (Northern Plains). Approximately 41.6% of AI/AN lung cancer cases were diagnosed before age 65 years compared with approximately 29.8% of NHW lung cancer cases. The overall percentage stage distribution was not different between AI/ANs and NHWs. Squamous cell carcinomas were slightly more common and adenocarcinomas were less common among AI/ANs than among NHWs. Lung cancer rates were not decreasing for AI/ANs as they were for NHWs. Data from this study clarified the need for culturally appropriate tobacco prevention and control policies and resources for AI/ANs in all regions, and especially in the Plains and Alaska.

Cancers of the urinary tract among American Indians and Alaska Natives in the United States, 1999-2004

Assessment of the kidney parenchyma ("kidney") and urinary bladder ("bladder") cancer burden among American Indians and Alaska Natives (AI/AN) has been limited. Using a database with improved classification for AI/AN, the authors described patterns of these 2 cancers among AI/AN and non-Hispanic whites (NHW) in the United States. Cases diagnosed during 1999 to 2004 were identified through National Program of Cancer Registries and the Surveillance, Epidemiology and End Results program and linked to the Indian Health Service (IHS) registration records. Age-adjusted incidence rates, rate ratios (RR), annual percent change, and stage at diagnosis were stratified by IHS Contract Health Service Delivery Area (CHSDA) counties to adjust for misclassification. Kidney cancer incidence among AI/AN in CHSDA counties exceeded that among NHW (RR, 1.51; 95% confidence interval [CI], 1.42-1.61), and was highest among AI/AN in the Northern Plains, Southern Plains, Alaska, and Southwest. Average annual increases were highest among AI/AN (5.9%) and NHW (5.9%) males aged 20 to 49 years, although statistically significant only among NHW. Conversely, bladder cancer incidence was significantly lower among AI/AN than NHW (RR, 0.40; 95% CI, 0.37-0.44). For both sites, AI/AN were significantly less likely to be diagnosed at an earlier stage than NHW. AI/AN have about 50% greater risk of kidney cancer and half the risk of bladder cancer than NHW. Although reasons for these enigmatic patterns are not known, sustained primary prevention efforts through tobacco cessation and obesity prevention are warranted.